The sum total of the researches, carried on with the expenditure of much effort and thought, and whose most important phases I have above endeavored briefly to sketch, has not sufficed, either to clear up our knowledge of this important division of infantile pathology. or to enable us to arrange in logical sequence the several links in the dis ease chain. The continued failure of agreement as to the classification of the various processes belonging in this group, for which processe.s every author working upon the subject proposes a new scheme of classification, demonstrates clearly that our knowledge of the nature and clinical significance of the disturbances of nutrition in early childhood has remained but a patchwork. I consider it my duty to precede the discussion of the subject with this confession.
We are concerned with the disturbances of nutrition from the food; these are manifested in a great variety of ways according to the chemi cal composition, biologic peculiarities, daily amount, intervals of ad ministration, bacterial uncleanliness, and admixture of toxines. We may also include with these eases others, of infants that come into the world with inferior equipment as a result either of premature birth and the corresponding undeveloped digestive power, or of insufficient func tioning power of the digestive apparatus from hereditary causes, and which even with the observance of all the precautions known to us appear to be imperiled throu,gh special susceptibility. In order to attain a phy.siologic basis from which we can gTasp and combat the causes of these disturbances of nutrition, we must start with. normal conditions, and must follow in their course of development, babies born at full term and brought up normally upon a sufficiently plentiful secretion of the mother's breast.
A digression is therefore pardonable into the subject of the physi ology of the nutrition of the human infant, our knowledge of which has been built on the ground of repeated and various collected observations. The newborn infant finds in the mammary glands of it, mother a fluid nutriment which is suited to its needs, and to the normal functionating of its digestive and assimilative apparatus. It is serviceable for the building up of the body substance, along the lines of normal devel opment, that is, with a proper distribution of the growth impulse through the various organs and tissues. This fluid itself develops according to the constantly changing needs of the infant. The sucking
reflex started by contact with the nipple permits it to take the food in an amount regulated by the need of sleep and the feeling of satiety, and to take in also £1 number of protective substances, which bestow upon it a certain power of resistance in the struggle against infections of various kinds. It takes in albuminous bodies which can perhaps be partly absorbed unchanged, but which can in any case be utilized by its body with comparatively easy chemical changes. It is able through mother's milk easily to maintain the constancy of its body temperature, to produce bowel movements in proper quantity and quality, to limit the secretion of its urine to proper amounts, to keep its intestinal flora normal, and also, perhaps, to strengthen its diges tive power by means of a number of ferments peculiar to the digestion of breast-milk, and to prepare it for future changes of nutriment. Thus a fluid nourishment streams into the infant in its natural state, at body temperature, and practically free of germs. In short we see here an example of how, everywhere in life, nature fits everything together in the smallest space and most economical way. If we are careful tbat the health of the nursing mother remains undisturbed, and that the taking of nourishment follows those intervals which we bave discovered, from the study of the course of digestion in nursing babies, to be most favorable (literature by von Hecker, Czerny-Keller and others), then the result follows that the newborn infant by its own work causes a normal development of the breast-glands of its mother from the stage of colostrum production to that of weaning. Under such conditions we notice a steady and undisturbed development of the child, which mani fests itself in a regular increase in the. body weight and stature, in a corresponding strengthening of the functionating power of the various organs, and in the occurrence of walking and dentition at the proper time. Deviations from the order briefly sketched above, have as their result disturbances of the function of the digestive organs, which soon manifest their unfavorable action upon the entire organism, and which can suddenly or gradually, lead to deep-seated alterations. These find their clinical expression in the different types of diseases of nutrition.
As the fundamental principles suggest that we take normal condi tions as our starting point, we shall begin with the